Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted as prior art by inclusion in this section.
Compared with downlink (DL) codebook design, there are significant differences in terms of network node implementation and deployment scenarios. Due to different gain set points, the issue of relative phase discontinuity (RPD) has been identified in Long-Term Evolution (LTE) mobile communication systems. With limited form factor, and given the immediate radiation/propagation environment is susceptible to effects such as hand-holding, rich local scatter and the like, possible antenna gain difference can also exist on the user equipment (UE) side. When multiple panels are used at a UE, there can be also the frequency coherence issue such as non-common mode phase noise. To complicate the situation even more, in 5th-Generation (5G) or New Radio (NR) mobile communication systems, both discrete Fourier transformation OFDM (DFT-OFDM) and cyclic-prefix orthogonal frequency-division multiplexing (CP-OFDM) waveforms are supported, and they have different requirements on the precoder in terms of peak-to-average power ratio (PAPR) preserving.